Species

cochlear nerve

Summary

Summary: The cochlear part of the 8th cranial nerve (VESTIBULOCOCHLEAR NERVE). The cochlear nerve fibers originate from neurons of the SPIRAL GANGLION and project peripherally to cochlear hair cells and centrally to the cochlear nuclei (COCHLEAR NUCLEUS) of the BRAIN STEM. They mediate the sense of hearing.

..sensory cells intact, but cause acute loss of afferent nerve terminals and delayed degeneration of the cochlear nerve. Results suggest that noise-induced damage to the ear has progressive consequences that are considerably more ..

..These results indicate that the changes in the anatomy of the auditory nerve induced by the combination of Ad.BDNF inoculation and the electrical stimulation used for testing improved functional measures of CI performance...

Olivocochlear efferents: anatomy, physiology, function, and the measurement of efferent effects in humans

..The results demonstrate not only the survival and migration of xenografted DRG neurons and stem cells along the adult auditory nerve but also the feasibility of a cell replacement therapy in the degenerated auditory system...

Auditory neuropathy characteristics in children with cochlear nerve deficiency

Craig A BuchmanDepartment of Otolaryngology Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USAEar Hear 27:399-408. 2006

To describe a group of children exhibiting electrophysiologic responses characteristic of auditory neuropathy (AN) who were subsequently identified as having absent or small cochlear nerves (i.e., cochlear nerve deficiency).

..These FFR findings support the viability of early, population-based 'predominant interval' representations of pitch in the auditory brainstem that are based on temporal patterns of phase-locked neural activity...

..Our findings also constitute an essential step toward a better understanding of the spike-train representation of time-varying stimuli initiated at this synapse, and thus of the fundamentals of temporal coding in the auditory pathway...

..Transplantation of progenitor cells together with established means to induce neural differentiation and fiber growth may facilitate strategies for better repair and treatment of auditory neuronal damage...

..However, it is probable that the form of the representation at the auditory cortex is fundamentally different from that at lower levels, in that stimulus features other than the distribution of energy across frequency are analysed...

..Across varying degrees of hearing loss, the ABR maintained a systematic relationship to auditory nerve fiber thresholds, and therefore has the potential to be used as a functional assay of cochlear pathology...

Variable long-term outcomes from cochlear implantation in children with hypoplastic auditory nerves

..In addition, it is possible that the physical properties of the cochlea, e.g., fluid-filled compartments and very limited space for cell proliferation, are unfavorable, at least in the normal cochlea...

..They also confirm the suggestion that changes in single-unit auditory nerve activity after cutting the olivocochlear bundle are probably a consequence of disrupting the more lateral of the two olivocochlear efferent pathways...

..These results suggest that dysfunction of the cochlear lateral wall and subsequent chronic reduction in the EP can directly affect the activity patterns of primary auditory neurons in a manner similar to that seen in aged gerbils...

..Overall, our data suggest that mechanical responses in the apex of the cochlea are considerably nonlinear and that these nonlinearities are of a different character than those known from the base of the cochlea...

Threshold tuning curves of chinchilla auditory-nerve fibers. I. Dependence on characteristic frequency and relation to the magnitudes of cochlear vibrations

..This null frequency was often not at the CF. At stimulation frequencies below the null, there was a progressive lag with sound level and a progressive lead for stimulation frequencies above the null. This was maximally 0.2 cycles...

Comparison of bandwidths in the inferior colliculus and the auditory nerve. I. Measurement using a spectrally manipulated stimulus

..It is shown here that this dependence of tuning on spontaneous rates is consistent with a previously unnoticed nonmonotonic dependence on iso-velocity criterion of the frequency tuning of basilar membrane vibrations...

Preliminary results of auditory brainstem implantation in prelingually deaf children with inner ear malformations including severe stenosis of the cochlear aperture and aplasia of the cochlear nerve

..The aim of our study is to present the results of 11 children where auditory brainstem implantation (ABI) was successfully performed to restore hearing...

Temporal processing from the auditory nerve to the medial nucleus of the trapezoid body in the rat

A G PaoliniDepartment of Otolarynology, The University of Melbourne, Royal Victoria Eye and Ear Hospital, East Melbourne, AustraliaHear Res 159:101-16. 2001

..Our results suggest that AVCN PL(N) units, representing globular bushy cells, are specialised for enhancing the temporal code at low frequencies and relaying this information to principal cells of the MNTB...

..thresholds encountered, even when data from many animals were combined, rarely exceeded 20 dB, suggesting that cochlear nerve responses obtained from this species display little inter-animal variability...

..Although we could not demonstrate a hearing loss in infants with moderate iron-deficiency anemia in this study, the relationship between severe iron-deficiency anemia and hearing loss or auditory dysfunction remains to be determined...

..We conclude that binaural sensitivity is more dependent on correlation sensitivity than has hitherto been appreciated and that the mechanisms underlying correlation sensitivity should be addressed in future studies...

Functional anatomy of the human cochlear nerve and its role in microvascular decompressions for tinnitus

..Comparing the reactions of a human and cat cochlear neuron, we find differences in spiking behavior, e.g. peripherally and centrally evoked spikes arrive with a time difference of about 400 mus in man and 200 mus in cat...

Two modes of release shape the postsynaptic response at the inner hair cell ribbon synapse

..5 T is often performed by using three-dimensional (3D) fast spin-echo or T2* techniques. We evaluated both techniques at 3 T in the preoperative assessment of patients being considered for cochlear implants...

Measuring the refractoriness of the electrically stimulated auditory nerve

..On the other hand, I(h), which is activated during hyperpolarization, does not play a large role in the basic onset response pattern but may regulate response threshold through its contribution to the membrane conductance...

Engraftment and differentiation of embryonic stem cell-derived neural progenitor cells in the cochlear nerve trunk: growth of processes into the organ of Corti

..Deeply inserted electrodes offer the possibility that apical stimulation may improve speech performances. Therefore, deep insertion is reasonable and should be performed in patients with profound or total hearing loss...

The temporal representation of speech in a nonlinear model of the guinea pig cochlea

..This information could be useful for determining optimal speech coding parameters for cochlear implant users on an individual basis...

Ensemble spontaneous activity in the guinea-pig cochlear nerve

G D SearchfieldDiscipline of Audiology and Division of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, New ZealandHear Res 192:23-35. 2004

..from the round window (RW) of the cochlea is referred to as the ensemble spontaneous activity (ESA) of the cochlear nerve. The ESA is considered to represent the summed spontaneous activity of single fibers of the auditory nerve and ..

Research Grants78

..The net effect of these hair cell actions is the production of discharge activity in the cochlear nerve. Tools are now available to dissect the processes in each of these cellular compartments and examine their ..

..how neurons in the cochlear nucleus respond to the onset and increasing levels of afferent input from the cochlear nerve during development with the implementation of mechanisms to regulate intracellular ion homeostasis...

..that stimulates the cochlear nucleus, can provide speech understanding in children and adults who have no cochlear nerve. These advances have benefitted substantially from the collective efforts of researchers in a broad array of ..

..The methods and specific aims can be summarized as follows: 1) Using horseradish peroxidase, individual cochlear nerve axons will be filled and their images reconstructed to study the development of the topographic organization ..

..manipulation of the EP, with particular attention to the proposed adaptation process; 4) the effect on the normal cochlear function, and on functional recovery to EP change, of a block on activity of the cochlear nerve.

..We expect the results of this work will guide future designs of cochlear-implant speech processors so that modulated stimuli can be better tailored to the encoding capacity of the user's auditory nerve. ..

..studies is to provide the database for interpreting observations obtained from physiological studies of the cochlear nerve or from psychophysical studies from which data are subsequent to transformations engendered by the auditory ..

..It will serve to catalyze interdisciplinary discussions among users, provide a valuable teaching tool for our trainees, and enhance the progress of biomedical research on hearing, vision, and voice. ..

..The intent of this study is to improve the perception of sound from the implant and potentially provide the cochlear implant user with the ability to hear more complex sounds. [unreadable] [unreadable] [unreadable]..

..We will also determine if reduced blood flow potentiates NIHL, in vivo. These studies will define new interventions and synergies at sites along the apoptotic pathway to optimize the prevention of NIHL. ..

..As we learn about how the somatosensory system modulates hearing, we will gain insight into somatic tinnitus that could contribute to the design of treatment strategies and a better understanding of tinnitus in general. ..

..Taken together, the three aims explore the major causes and effects of metabolic presbyacusis and have direct application to future interventions to help restore age-related hearing loss. [unreadable] [unreadable]..

..Current treatments for hearing loss involve sound amplification via hearing aids or direct stimulation of the cochlear nerve, bypassing the damaged sensory epithelium. There are no known treatments for loss of vestibular function...

..Aim 3 will identify changes in the central auditory pathway that result from deafness and chronic electrical stimulation and, thus, will inform decisions regarding age of implantation and patterns of chronic stimulation. ..

..plans to identify ultrastructurally the morphological and immunochemical character of vesiculated endings that express GAP-43 in the inner spiral bundle, the only neuronal pathway that contains this growth protein in the adult cochlea. ..

..Envelope cues suffice for these S/N comparisons. However, fine structure will be necessary for localization tasks based on interaural time differences in bilateral implant simulations (Experiment 2b). ..

..for hearing preservation following damage to the auditory system, such as through design or activation of cochlear nucleus prostheses, and for the design of speech recognition systems used in complex acoustic environments ..

..Therefore, this research has additional significance in that it may lead to development of clinical tools that will target sources of reduced temporal processing. [unreadable] [unreadable] [unreadable]..

..In unilateral implantees, this work has already demonstrated substantial benefit in a limited number of subjects;it is our goal to deliver these benefits to the broader population of implant recipients. ..